This invention pertains to a method of assaying vinyl acetate and more particularly to an assay of vinyl acetate in ambient air.
Environmental restrictions and regulations relating to the presence of chemicals in the ambient air present in plant and other working areas are particularly stringent with respect to monomeric materials. A need arose therefore for means of monitoring the levels of widely used monomers, such as, vinyl acetate which is used in a plethora of polymeric materials.
One of the difficulties associated with taking routine assays of vinyl acetate in ambient air present in industrial polymerization plants is the fact that it hydrolyzes with water to form acetic acid and vinyl alcohol. The latter immediately undergoes a rearrangement to acetaldehyde. Furthermore, upon vaporization from the liquid state, vinyl acetate loses any polymerization inhibitor which was present in the liquid vinyl acetate. This makes any analytical procedure more difficult since vinyl acetate which polymerizes will not appear in the final analysis as a monomer. It is common to inhibit vinyl acetate liquid with from 5 to about 20 parts per million of a free radical stabilizer, such as, hydroquinone. The boiling point of hydroquinone is far too high to permit its evaporation with vinyl acetate to the vapor state. The problem of analyzing ambient air to which employees in a vinyl acetate polymerization plant are exposed is therefore made inaccurate because of the hydrolysis or polymerization of vinyl acetate after collection of a representative air sample prior to analysis.
It is therefore an object of this invention to provide a facile method of determining the vinyl acetate monomer levels in random ambient air samples collected in a working vinyl acetate plant during the time of worker exposure to this monomer.